Tubular cam operating safety device



Sept. 1, 1970 D TROLL 3,526,733

TUBULAR CAM OPERATING SAFETY DEVICE Filed Oct. 5, 1968 United States Patent 3,526,733 TUBULAR CAM OPERATING SAFETY DEVICE Dennis Graham Troll, The Green, Henton, Oxfordshire, England, assignor to Dewhurst & Partner Limited Filed Oct. 3, 1968, Ser. No. 764,765 Int. Cl. E05f 15/02; H01h 3/16 US. Cl. 20061.43 3 Claims ABSTRACT OF THE DISCLOSURE An elevator lift door safety device consists of a tubular member mounted extending along the door edge to engage an obstruction, an operating shaft extending laterally into the tubular member, and a cam on the operating shaft inside the tubular member. The cam consists of a cross shaft normally skewed relative to the tubular member, carrying a pair of rollers. Movement of the tubular member in any direction aligns the cross-shaft therewith, thereby rotating the operating shaft to operate the safety device.

The present invention relates to a safety device to stop movement of a member, such as for example a door of a lift, upon encountering an obstruction.

It is an object of the invention to provide a safety device suitable for mounting on the edge of a lift door, and operative to stop closure of the door when engaged from any direction, that is, from the side, the back or the front of the lift door.

According to the invention, there is provided a safety device suitable for mounting on the edge of a lift door or other sliding door, comprising a switch mechanism for mounting on the door, an operating shaft extending from the mechanism, the shaft being rotatable about its axis to operate the switch mechanism, a tubular, part tubular or other hollow member arranged to extend along the door edge for engagement by an obstruction, the shaft extending laterally into the said member, and a cam on the shaft engageable by the member to rotate the shaft upon relative movement of the member axially or sideways of the shaft.

The invention will be described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of a door with a safety device in accordance with the invention; and

FIG. 2 is an enlarged perspective view of part of FIG. 1, part broken away.

The door is provided with a safety device 11 which comprises two electric switch mechanisms 12 and 13 mounted near the door edge 14. Two operating shafts 15 and 16 extend one from each switch mechanism 12 and 13- respectively, the shafts 15 and 16 being rotatable about their axes to operate the respective switch mechanisms 12 and 13. A tubular member 17 is arranged to extend along the door edge 14, for engagement by an obstruction (not shown). Each operating shaft 15, 16 extends laterally into member 17, as shown.

As shown in FIG. 2, in which member 17 is partly broken away to reveal the interior, a cam 18 on the end of shaft 15 takes the form of a cross-shaft 19, normally skewed to the axis of member 17, and two rollers 21 and 22 on the ends of cross-shaft 19. The cross-shaft 19 is normally held thus skewed by a tension spring 23.

A similar cam is provided on the end of shaft 16.

, 3,526,733 Patented Sept. 1, 1970 "ice Switch mechanisms 12 and 13 are identical. Each consists of the tension spring 23, a flanged support plate )24, bolted to the door 10, a sleeve 25 welded to the support plate flange 24a, end on, to mount the operating shaft 15, 16, the tension spring 23, an electric switch contact unit 26 and a block 27 mounted on the operating shaft 15, 16. One end of the spring 23 is attached to the support plate flange 24a, and the other end to block 27. Contact unit 26 has a vertically reciprocable operating member 28, fitted with a bellows-type seal 28a and terminating at its lower end with a ball bearing 28b. The ball bearing 28b engages the upper surface 27a of block 27 to one side of the centre line, as shown. Thus anticlockwise roation of the block 27 (as seen in FIG. 2) will raise the operating member 28 to operate contact unit 26. However, mere axial movement of block 27, without rotation, will be of no effect on member 28. A string or wire cord 29 is connected between the rear ends of shafts 15 and 16 and passes round pulleys 31 and 32, for the purpose of retracting member 17 except when the doors are closing or opening, in a manner to be described.

In operation, the door 10 moves to the right to open and to the left to close. During movement of the door 10, the cams on the operating shafts 15 and 16 position themselves on a diameter of member 17 in skewed positions, under the action of springs 23. If member 17 is engaged by an obstruction, either from the side, the back or the front of door 10, member 17 operates one or both of the swift mechanisms 12 and 13' by camming the respective cross-shaft into a vertical position, rotating the operating shaft 15, 16.

With the door 10 in the fully open or fully closed position, catches (not shown) on the door frame engage the cord 29, to draw both of the operating shafts 15 and 16 to the right until member 17 abuts the flange of support plate 24, preventing operation of switch mechanisms 12 and 13.This is of especial use on centre opening doors and for single sliding doors which abut to a slamming post.

While the shafts 15 and 16 are pulled to the right by cord 29, there is no turning moment on the shafts 15 and 16. Therefore the block 27 does not rotate to raise member 28 and thereby operate contact unit 26 but merely moves axially, without effect.

In a modification, not shown, member 17, which is tubular, is replaced by a member of U cross-section, secured to two short tubular members into which operating shafts 15 and 16 extend.

What is claimed is:

1. A safety device suitable for mounting on the edge of a lift door or other sliding door, comprising a switch mechanism for mounting on the door, an operating shaft extending from the mechanism, the shaft being rotatable about its axis to operate the switch mechanism, a tubular, part tubular or other hollow member arranged to extend along the door edge for engagement by an obstruction, the shaft extending laterally into the said member, and a cam on the shaft engageable by the member to rotate the shaft upon relative movement of the member axially or sideways of the shaft.

2. A device according to claim 1 wherein the cam is formed by two rollers rotatably mounted on a cross shaft which is normally skewed to the axis of said tubular, part tubular or other hollow member.

3 3. A device according to claim 1 wherein said shaft is retractable upon the door becoming fully or almost fully open and/or fully or almost fully closed so as to withdraw said tubular, part tubular or other hollow member into an inoperative position.

References Cited UNITED STATES PATENTS 1,890,809 12/1932 Forman 49-27 X 2,687,455 8/1954 Norman ZOO-61.43 3,159,728 12/1964 Urquhart ZOO-61.43

FOREIGN PATENTS 688,053 6/1964 Canada.

ROBERT K. SCHAEFER, Primary Examiner R. A. VANDERHYE, Assistant Examiner U.S. C1. X.R. 49-27; 200-153 

